The present invention relates to a vacuum circuit breaker for use in the electric power substation, equipment for controlling the opening and closing of industrical powers, and the like.
FIG. 1 shows a conventional vacuum circuit breaker. A vacuum circuit breaker 100 includes a vacuum interrupter or valve 102 provided with fixed and movable electrodes, and main circuit conductors 104 and 106. The fixed electrode of the vacuum valve 102 is electrically connected to the main circuit conductor 104 while the movable electrode thereof to the main circuit conductor 106 via a flexible conductor 108, thus forming a main circuit line. The movable electrode of the vacuum valve 102 is connected through an insulating rod 110 and a link 112 to an operating mechanism 114, which is operated to cause the movable electrode to close and open the main circuit line. The fixed electrode and the main circuit conductor 104 of the vacuum valve 102 are fixed via a support 116 to one end of a support insulator 118 while the main circuit conductor 106 thereof via a support 120 to one end of a support insulator 122. The operating mechanism 114 is attached to an attachment plate 124, which is formed integral to a base 128 provided with wheels 126. The other ends of the support insulators 118 and 122 are fixed to the attachment plate 124, respectively. The support insulators 118 and 122 mechanically support but electrically insulate the vacuum valve 102. Since the vacuum valve 102 is cantilever-supported relative to driving force applied from the operating mechanism 114 to close and open the vacuum valve in the arrangement as described above, the main circuit conductors 104 and 106 are connected integrally with the base 128 by means of reinforcing insulating studs 130 and 131. The vacuum circuit breaker 100 has a plurality of vacuum valves, for example, two vacuum valves, having such arrangement as described above. The vacuum circuit breaker 100 thus formed is required to have a predetermined insulating distance between two adjacent vacuum valves 102 so as to resist voltage the employed. When the insulating distance is set using atmosphere, the whole of vacuum circuit breaker becomes large-sized. Therefore, an insulating barrier 132 is arranged between two adjacent vacuum valves 102 to make the vacuum circuit breaker 100 small-sized. This insulating barrier 132 is attached to the attachment plate 124 and the base 128 by means of metal fittings.
As described above, the insulating barrier, reinforcing insulating stud, support insulator, support and the like are formed as separate individual members and these thus formed are assembled with one another to form the conventional vacuum circuit breaker. Therefore, the conventional vacuum circuit breaker is large in number of its parts, troublesome in adjusting their dimensions, difficult in assembling them and high in cost. In addition, the attachment plate to which the vacuum valve, operating mechanism and the like are attached and which is formed integral to the base makes it difficult to apply the conventional vacuum circuit breaker to enclosed switchgears tiered in one or two stages by changing the height of main circuit conductors therein.